This invention relates to improvements in the welding of thermoplastic tubes. Various techniques are known for such welding operations. Copending application Ser. No. 51,390, filed May 18, 1987, now U.S. Pat. No. 4,793,880, the details of which are incorporated herein by reference thereto, discusses prior techniques as well as the particular techniques which are the subject of that invention. A common use of such techniques is in dialysis when it is necessary to provide a patient with a fresh supply of liquid dialysate. Under such circumstances the tube containing the old dialysate which leads from the patient to the supply is severed. The same apparatus severs a tube leading from the new supply. The conventional techniques involve realigning the cut tubes so that the tube section from the new supply becomes aligned with the tube section from the patient. These aligned tube sections are then welded together to provide the patient with fresh dialysate.
The main emphasis in the techniques used heretofore have been concerned with the welding of fluid-filled tubes. With such techniques means had to be provided to flatten or seal each tube at two spaced locations so that a cutting device, usually a heated wafer, may cut through the tube between the two spaced locations.
The conventional approaches taken heretofore have also been generally confined to cutting through parallel tubes and then realigning the tube so as to form a single welded tube. Under certain circumstances, however, it would be desirable if the techniques could be utilized for welding a branch tube to a main tube.
It would also be desirable if techniques could be provided which are capable of welding fluid filled tubes wherein the cutting and welding steps take place in a portion of the tubes where there is no fluid.